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Eppur Si Muove: Galileo’s Big Night, 407 Years Ago Today

7 Jan 2017, 20:21 UTC
Eppur Si Muove: Galileo’s Big Night, 407 Years Ago Today
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Jupiter and its four largest “Galilean” moons photographed on April 16, 2016. © Jason Major
407 years ago tonight, on January 7, 1610, the Pisan astronomer Galileo Galilei looked up at a brilliantly-shining Jupiter through his own handmade telescope and saw three bright little “stars” next to it, stirring his natural scientific curiosity. Further observations over the next several nights showed that the planet wasn’t moving relative to the little “stars” as it should if they were distant background stars, but rather the bright objects (of which he soon saw four) were moving along with Jupiter. Galileo correctly concluded that those little objects weren’t stars at all but rather moons that orbited the distant planet—and, most importantly, not the Earth. This cosmic revelation forced a change of the entire view of our solar system (causing no end of trouble for Galileo as the Church didn’t appreciate a challenge to their Earth-centered Universe) but also opened the door for the discovery of many more moons around other planets.

Drawings from Galileo’s notebook
Jupiter is now known to have at least 50 moons, with possibly as many as 67.
1636 portrait of Galileo.
As a result of his research and publications regarding ...

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